Field of the Invention
The invention relates to a transfer drum in a sheet-processing or sheet-fed printing press having a support surface formed at least segmentally of individual punctiform support elements disposed on the circumference of the transfer drum.
When thicknesses of paper are being processed in sheet-processing printing presses, especially in a perfector printing operation, smearing problems occur with freshly printed sheets on the transfer drum.
To avoid this smearing problem, it has become known heretofore, for example, from the published German Patent Document DE 39 29 228 A1, to dispose, on a shaft support, brackets having punctiform support elements corresponding to the circumference of the sheet transfer drum, when cardboard or pasteboard is being processed. Due to these measures, the sheet rests on the support elements only in adjustable regions. When thin paper is being processed, support brackets with smaller circumferential dimensions are provided. A disadvantage of the construction according to the aforementioned published German Patent Document DE 39 29 228 A1 is that the support elements are used both when cardboard is being printed and when thin paper is being printed. Consequently, air turbulence, especially when thin paper is being printed, causes undesired fluttering of the sheets and leads to sheet guidance problems which impair the quality of the printed products.